Nozzle for sand-blast apparatus



April 2g, 1930. w. ECKLER 1,755,575

NOZZLE FOR SAND BLAST APPARATUS Filed July 19, 1928 lhrenlor: f' IM pc/Wer Patented Apr. 22, 1930 UNITED STATES WILHELM ECKLER, OF ALTONA-OTTENSEN, GERMANY NOZ'ZLE FOR SAND-BLAST APPARATUS Application filed July 19, 1928, Serial' No. 293,967, and in Germany August 20, 1925.

The present invention relates to a nozzle arrangement for sand blast apparatus in which the sand in a closed container is under the pressure of a column of compressed air,

which enters below the sand container as well into a pipe into which the sand container continuously delivers accurately regulated quantities of sand which enter the interior of the pipe under the action of gravity.

Such sand blast apparatus are provided for certain purposes, more particularly for playing on articles resting on a rotatable or reciprocating table surface, with revolving or oscillating nozzles.

According to the present invention in such 4revolving or oscillating nozzles or sand blast apparatus working under pressure, an arrangement is provided, which is intended t0 prevent the revolving or oscillating nozzles becoming stopped up, more particularly through sand which has become moist.

Most interruptions in the Working of pressure-operated blast apparatus are due to the sand becoming moist. In mostcases the stoppage occurs at places Where the direction changes in the nozzle conveying the mixture of sand and compressed air. At these places Where the direction changes the velocity at which the sand and compressed air mixture travels is changed, generally being reduced. Owing to the increased friction which occurs at vthe same time at these places, the sand which has become moist adheres to the sides and, after the moisture in the. sand has dried out or evaporated, accumulations of adhering sand, which constantly increase, are formed,until finally the passage for the mixture of sand and compressed air becomes so narrow that, it is no longer wide enough to 10 fulfill its purpose at all. The stopped up places must then be cleared byrst cleaning outl the sand passages in the nozzles, in order that the sand blast apparatus can be put into operation again.

As the compressed air is in every case produced in compressors and heat is in any case developed in the compressors during the compression of the air, the moisture content in the air compressed in the compressors is not i0 detrimental, as long as the heat,in thecom# pressed air keeps the moisture in the form of mist or vapour. Only when the heat drops to such an extent that the vapour changes to liquid condensates, will these small drops of water exert a detrimental elect on the sand admixed to the compressed air in the sand blast apparatus in the manner already referred to. Furthermore, as long as the mixture of compressed air and sand in the pipes connected to the sand container, more particularly in the passages of the nozzles, retains sufficient velocity of ilow, the danger of theormation of liquid condensate from the moisture contained in the compressed air and consequently the danger of stoppages through sand which has become moist, is relatively negligible.

The danger, however, becomes great when the velocity'of low of the compressed air" and sand mixture is greatly reduced or completely stops, which will always be the Case when, from any cause, for instance for placing fresh articles to be cleaned on the table which lies below the Vrevolving or oscillating nozzles or for altering the position of the articles on the said table, the latter has to be brought to rest. The reason for this is, that hitherto, for preventing kthe outflow of the, compressed air and sand mixture from the nozzle which is put out of operation and for preventing damage, which would result throughthis continued outflow of the compressed air and sand mixture at a single place only, the compressed air cock and the sand supply cock have been closed. Through these interruptions in the llow of the compressed air the vapour carried along by the latter lmight be cooled off to such an extent that it would be converted'into the liquid form and on coming in contact with the sand, would moisten the latter to such an extent as to result in the formation of lumps and the occurt rence of stoppages as explained above.

The object of the nozzle arrangement acis intended automatically to prevent the sand being carried along at the place at whichV otherwise the mixture of the air and the sand takes place, when onl the revolvingI or the oscillation of the nozz es has previously been stopped, but the air supply itself need not be stopped. In addition to this in co-opera- 4tion with the peculiar air supply below the -cording to the invention,

Figure l is a ront'elevation of the pressure-operated sand blast apparatus in part vertical section through the sand container and the nozzle' arrangement and rotary table lying below the same.

Figure 2 is a longitudinal section through the nozzle arrangement according to Figure `Vl, to an enlarged scale.

1 is a grid-like table mounted on the shaft 2 and journalled in the footstep bearing 3, which acts as the support for the articles to be cleaned and is positioned below the ixed cover plate 4 in a frame 5 which encloses the table with the exception of a charging opening which can be covered in a known manner by rubber curtains.

On the top of the frame 5 is another closedy frame 6 in which is a bucket conveyor of the known kind (not shown) which conveys the used sand from the bottom of the frame 5 to the top, where-it exposes it to the action of an exhaust fan which blows away the fine admixtures ci dust and conveys the still useful grains of sand through a separator 7 and a downcomer 8 into a double hopper 10, 11 which rocks about the point 9. From the double hopper 10, 11, the sand passes in Ineasured quantities into the sand container 12. All the parts described are known and do not form the subject of the present invention.

AAt the bottom of the same container 12 is a downwardly directed sand outlet passage 13 which discharges into a removable outlet opening 13a which can be varied in diameter. The outlet opening 13B is at a short distance above the surface of a late 14, such that the sand falling down t rough 13, 13a can accumulate on the surface of the plate 14a till it forms a pile, the angle of slope of which bears such a relation tothe distance of the arts 138, 14, that, when no vibrations are imparted to the plate 14, the apex of the angle of slope extends into the opening of 13a, closing the said opening, so that the sand seeking to flow out of the opening 13a has no outlet` but is checked in its motion. The parts 13, 14 are surrounded by a rotatable pipe 19 which is connected in a suitable manner, for instance screwed, to the nozzles 15, 16, which in the present instance are capable of revolving and are held together by a middle piece 17. This surrounding pipe 19 is driven by a toothed wheel 18 and rests on a ball bearing 21 provided-on the part 22 of the :trame resting on the cover 4. The surrounding tube 19 is shut off from the sand container 12,:by a stuffing box 23. This is eil'ected by the funnel-shaped casting 24, which forms the foot of the container 12, being constructed so as to form an annular air chamber 25 for the entrance of the compressed air flowing through the supply pipe 26, a saddle-shaped flange 25n engaging over the upper end of the surrounding pipe 19. rlhe compressed air entering 25 through 26, the pressure of which is the same as that of the column of air contained in the sand container 12, therefore flows over the bent-over flange 25a downwards into the annular space lyingbetwcen the parts 13, 14, on the one hand, and the insideof the wall of the surrounding pipe 19, on the other hand, and thence into the passages of the distributing pipe 17 and enters nozzle pipes 15, 16 which are bent over at an angle. This has the advantage that, should there by any chance be a stoppage in the annular space or in the passages of the parts 15, 16, 17, such a stoppage cannot result in a portion of the loose sand in the annular space being whirled upwards or even being forced into the gaps at the points between the rotating tubular part 19 and the tubular part 24 surrounding the stuing box 23. Such a penetration of sand into the gaps between the rotating and fixed part of the sand container would very soon result in considerable friction and in the said parts being badly worn, which would eventually cause considerable trouble in the operation of the apparatus. Should astoppage occur in the annular space, the air entering at 26, 25 and iowing downwards wculd at least not be able to How any further; it would stagnate, but would never cause the loose sand in the pipe 19 to whirl about or upwards.

As long as there is no stoppage in the an nular space between the parts 13, 14, 19, the air entering at 26, 25 and viowing downwards always blows the annular space above the plate 13a completely clean and prevents any grains of sand or dust from rising. It mixes at the gap between the plate 14 and the outlet opening 13a evenly with the sand trickling downwards out of the pipe 13 over the angle of slope of the accumulation on the plate 14, as long as the vibrations due to the revolving or oscillating motion of the nozzle parts adjoining the pipe 19 render such a trickling down of the sand unavoidable. On the toothed wheel 18 coming to rest, however, in which case these vibrations will cease, the accumulation of sand on the plate 14 will rise, forming a steeper angle of slope and will automatically close-the opening`13'1. so that no more sand will trickle down. The compressed Jair flowing through the annular space between the parts 13, 14, 19 willthen force out only the remainder of the sand which, during the operation of the nozzles, has passed into the passages leading to the same. When all this sand has been removed from the nozzles in this manner, only the compressed air will continue to flow out of 26' and will escape unused without carrying sand along .with it from the plate 14, as long asl the operations 'which are performed while the turn table 1 is at rest, namely the turning over or .the removal of the articles to be treated, continue.

Through the compressed air being blown out in this way any forming of condensate is prevented effectively. As compared with this prevention of disturbances in the operation of the apparatus the loss of compressed air during the periods of rest of the revolving or oscillating nozzles represents a relatively small disadyantage. It 1s all the more negligible in comparison with the advantages due to the prevention of interruptions in the operation of the plant, since the compressors in any case are not stopped durin the various pauses inthe operation of sand last apparatus, but continue to operate.

What I claim is: v

v1. A blast nozzle arrangement for sand blast apparatus, comprising a sand container, an outlet Jfor the sand at the bottom of the sand container, a revolving table underneath the sand outlet, a rotatable tubularmember below the sand container, above the revolving table and surrounding the sand outlet, sand nozzles secured to the lower end of the rotatable tubular member, the said tubular member Abeing adapted to guide sand from the sand outlet to'the sand nozzles, an inlet for admittin a gaseous driving fluid into the rotatable tu 'ular member, a sand accumulating member mounted inside the rotatable tubular-member and underneath the sand outlet in such a position as to leave an annular gap between the tubular member and the sand accumulatingfmember, the said gap leading tothe sand nozzles, and the said sand accumulating member being adapted to spill -sand uniformly into the annular gapwhenever the f nozzles are rotating, owing to the vibration caused by such rotation.

the sand outlet, a rotatable tubular member below the sand container, above the revolv-` ing table and surrounding the sand out-let, sand nozzles secured to the lower end of the rotatable tubular member, the 4said tubular member being adapted to guide sand from the sand outlet to the sand nozzles, an inlet for admittinof a gaseous driving liuid into the rotatable tiibular member, and a sand accumulating plate mounted inside the rotatable tubular member and underneath the sand outlet in such a position as to leave between the tubular member and the sand accumulating member an annular gap leading to the sand nozzles, the sand accumulating plate being so close to the sand outlet that when the nozzlesl are'stationary. a heap of sand accumulates thereon and projects into and closes the said sand outlet, and the Said'sand .accumulating plate being adapted to spill sand uniformly into the annular gap whenever the nozzles are rotating, owing to the vibrationcaused by such rotation.

3. A` blast nozzle arrangement ,for sand blast apparatus, comprising a sand container, an outlet for the sand atthe, bottom of the sand container, a` revolving tablexunderneath the sand outlet, a rotatable tubular member below the sand container, above the revolving table and surrounding thefsand outlet, sand nozzles secured to the lower end of the rotatable tubular member, the said tubular member being adapted to guide sand from the sand outlet to the sandinozzles, an annular member closing the rotatable tubular member at the top and overlapping the upper edge of the said tubular member, an inlet in the said annular member for admitting a gaseous driving fluid into the rotating tubular member, and a sand accumulating plate mounted inside the rotatable tubular member and underneath the sand outlet in such-a position as to leave between the tubular member and the sand accumulating member an annular gap leading to the sand nozzles, the sand accumulating plate being so close tothe sand outlet that when the 'nozzles are stationary a heap of sand accumulates thereon and projects lnto and closes the said sand outlet and the said sand accumulating plate being adapted to spill sand uniformly into the annular gap whenever the nozzles are rotat1n g,ow1ng to the vibration caused b such rotation.

In testimony whereo I have slgned my name to this specification.

WILHELM ECKLER.v

2. .A blast nozzle arrangement for ysand blast apparatus,lcomprising a sand container, an outlet 'forthesand at the bottom of the sand container, arevolving. table underneath 

